Which of the following statements are correct about $\mathrm{Zn}, \mathrm{Cd}$ and $\mathrm{Hg}$ ?
$A$. They exhibit high enthalpy of atomization as the d-subshell is full.
$B$. $\mathrm{Zn}$ and $\mathrm{Cd}$ do not show variable oxidation state while $\mathrm{Hg}$ shows $+\mathrm{I}$ and + $II.$
$C$. Compounds of $\mathrm{Zn}, \mathrm{Cd}$ and $\mathrm{Hg}$ are paramagnetic in nature.
$D$. $\mathrm{Zn}, \mathrm{Cd}$ and $\mathrm{Hg}$ are called soft metals.
Choose the most appropriate from the options given below:
$B$, $D$ only
$B$, $C$ only
$A$, $D$ only
$C$, $D$ only
Properties common to the elements manganese, iron, cobalt, nickel and copper include the ready formation by them all of
$(I)$ coloured ions in aqueous solution
$(II)$ oxides of nitrogen are formed on reaction with concentrated $HNO_3$
$(III)$ chlorides of formula $MCl_2$ and $MCl_3$
Manganese steel is used for making railway tracks because
$Fe,$ $Co$ and $Ni$ have valuable catalytic properties in process involving
Although $\mathrm{Cr}^{3+}$ and $\mathrm{Co}^{2+}$ ions have same number of unpaired electrons but the magnetic moment of $\mathrm{Cr}^{3+}$ is $3.87$ $B.M.$ and that of $\mathrm{Co}^{2+}$ is $4.87$ $B.M.$ Why ?
Which of the following compound is coloured ?